Liquid-electrode lightning-arrester for multiphase low-voltage circuits.



E. E. F. CREIGHTON. LIQUID ELBGTRODE LIGHTNING ARRESTER FOR MULTIPHASE LOW VOLTAGE GIRGUITS. APPLICATION IILBD SEPT. 2, 1908.

1,004,534. Patented Sept. 26, 1911.

Elmer BF Cr i hton, @www new@ Ifttg.

'l UNITED sTATEs PATENT oEEroE.

i ELMER E. F. CREIGHTON, OF SCHENECTADY, NEW YORK ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION 0F NEW YORK. i

LIQUID-ELECTROIIE LIGHTNING-,ARRESTER FOR MULTIPHASE LOW-VOLTAGE CIRCUITS.

Specification of I.etters Ilatent.

Patented Sept. 26', 1911.

Application ledvSeptemher 2, 1908. Serial No. 451,303.

'To all whom it may concer'n Be it known that I, ELMER E. F. CBEIGH- ToN,-a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Liquid-Electrode Lightning Arresters forV Multiphase Low- Voltage Circuits, of which the following is a speclication.

This invention relates to devices for protecting alternating current systems from the destructive effects of lightning, whether transitory or continual.

In a former application, Serial No. 358,7 77 I vhave disclosed a lightning arrester in which a' copper electrode is placed close to or dipping below the surface of a liquid electrode, composed of a suitable electrolyte, whereby high frequency currents exceeding 1500 volts will be freely discharged, but all below that` value will be held ack.

this form of lightning arrester, and consists in a single cell adapted to take care of light-v ning discharges froma polyphase line. To this end the cell contains a plurality of anodes connected respectively to the several line conductors, the liquid cathode grounded.y

This arrester is designed for use on systems whose potential is below 1500 volts. There will be no leakage from line to line, or from line to ground through the ground connection under normal conditions due to the series gap. r But if the potential on any one or more of the line conductors becomes dangerously high, owing to lightning of any kind,'and exceeds the gap spark potential, the excess of' otential will be at once relieved, establis in an arc from the anode connected with said conductor to the liquid electrode and thence .to ground. By combining the three anodes in one cell, a compact and inexpensive device is produced.

In-the accompanying drawing, Fiire is a perspective view of an arrester ein odying my invention; Fig. 2 is a diametrical section thereof; Fig. 3 shows a modification; and Fig. 4 is a section of a portion of Fig. 3.

Referring first to Figs. 1 and 2: The cell.vr

being holes insaid cover. Under the head of the bolt is an annular disk or washer 4 of metal,

and the lead 5 from. the line conductor 6 is clamped upon said washer by the head of the bolt. Adjacent to each binding post is ahole in the cover through which passes a tube 7 of glass, porcelain or ,other refractory. insulating material. A flange 8 on said tube supports it in said hole, and above said ange is placed a washer v9 of metalV arranged with its-edge at a suitable distance from the washer 4 to form a spark-gap. A

copper wire 10 is run through the tube 7 and its upper end is soldered to the washer 9.

Thelower end of said wire is close to or dips below the surface of a volume of electrolyte 11 which partially fills the jar. The tube extends preferably nearly to the end of the wire. A tube 12 is suspended in the jar by I. its flange 13, and serves to protect 'a wire 14 which extends down into thefelectrolyte and has a considerable surface exposed thereto.

The upper end ofthe wire 14 is grounded at 15. VThe cover has a vent hole provided with ay guard 17 on the under side of the cover a little below the vent, to prevent the electrolyte from being thrown out of the vent during the active periods of the arrester.

In Fig. 3 the grounded wire 14 is omitted, and the jar 18 itself constitutes the ground connection, being in this instance made of metal, such as cast iron, and having, if desired, a grounded wire 19 attached to it. Thecover 20 is made of glass or porcelain, to facilitate the insulation of the spark-gap washers 4 9 and the anodes l0.I Whenl this cell is connected to a system having a potential of less than 1500 volts abnormally high potentials are discharged freely on account `of the limiting potentials of the spark-gap and of the are at theliquid surface, butthe followin low volta e dynamic current is quickly s ut 0H b t e failure of the arc topersist at the sur ace of the electrolyte.

This arrester iS simple and compact and takesI the place of three or more singleanode cells when a multiphase system is to be protected. l

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A li uid electrode lightning arrester for low vo tage. n iultipha'se systems compris ing a jar containing a volume of electrolyte, a plurality of ano es m operative relation to said electrolyte and proportioned to cause the current density at voltages below the critical limiting voltage of a true liquid electrode arrester to develop an arc which materially increases resistance to current flow, electrodes spaced apart to form a spark ga connected res ectively with each anode an each line'con uctor of said system, and a ground connection for said electrolyte.

2. The combination with a jar having a cover of insulating material and containing a volume of electrolyte, of a plurality of tubes of insulating material depending from said cover, metallic through said tubes and dipping into the electrolyte, said anodes Abeing proportioned to cause the current density at voltages below the critical limiting voltage of a true liquid electrode arrester to develop an arc which materially increases resistance to current flow, electrodes spaced apart to form in series with each anode a spark gap which breaks down at potentials which will cause suflicent current to develop the arc to the electrolyte, and means for grounding said electrolyte.

. 3. The combination with a jar havinga cover of insulating material and containing an electrolyte, ot binding posts on' said anodes extending cover, metallic washers connected with said posts, tubes of insulating material depending through said cover, metallicl washers on the"upper end of said tubes in spark-gap relation to 4saidother washers, and metallic anodes in said tubes connected with lthe Washers thereon and coperating with said electrolyte to develop from the anode to the electrolyte upon breakdown of the spark gap an arc which increases the yresistance to current flow.

4. The combination with a grounded metallic jar, of a cover of insulating material, a plurality of metallic anodes sus ended from said cover, spark-gap electro es for each anode, and a liquid cathode in said jar in operative relation toy said anodes the im- 'mersed surface of said anodes being such ,that upon breakdown of said spark gap the current density develops between the anode and the .liquid cathode an arc which materially increases the resistance to current 

